Vortex formation and frequency tuning of periodically-excited jet diffusion flames
Vortex formation and frequency tuning of periodically-excited jet diffusion flames
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DOI：
10.1016/j.proci.2020.08.015
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发表时间：
2020-10
期刊：
影响因子：
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通讯作者：
X. Xia;C. Fu;Yifan Yang;Xiaoyuan Yang;Yi Gao;F. Qi
中科院分区：
文献类型：
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作者：
X. Xia;C. Fu;Yifan Yang;Xiaoyuan Yang;Yi Gao;F. Qi
本文对周期激励下喷流扩散火焰的涡系形成和频率调谐进行了实验研究。最先进的激光诊断技术被应用于提供火焰和流动结构的时间分辨测量。结果表明，火焰表面变形与内涡环对流是同步的，表明内涡环在影响火焰动力学中起着至关重要的作用。对涡旋形成和演化的定量研究旨在了解两个机制：IVR是如何形成的，以及它是如何调节到扰动燃料的强迫频率的。环量增长的预测与实验数据的定性吻合验证了经典启动涡流模型在解决当前问题时的适用性，表明涡流增长主要由上游燃料的剪切层决定。旋涡调谐与主IVR的脱离密切相关，当燃油射流和同向流之间的剪切改变方向时，主IVR的脱离被归因于次要的“剃刀涡”。
This paper presents an experimental study on the vortex formation and frequency tuning of jet diffusion flames under periodic excitations. The state-of-art laser diagnostic techniques were applied to provide temporally-resolved measurements for flame and flow structures. The results show that the fame surface deformation is synchronized with the convection of the inner vortex rings (IVRs), demonstrating the crucial role of IVRs in affecting the flame dynamics. The quantitative study on vortex formation and evolution is intended to understand two mechanisms: how the IVR forms, and how it is tuned to the forcing frequency of the perturbed fuel. The qualitative agreement between the predicted circulation growth and experimental data verifies the relevance of the classical starting vortex jet model in addressing the current problem, indicating the vortex growth is mainly dictated by the shear layer of the upstream fuel. The vortex tuning is closely related to the detachment of the main IVR, which is attributed to a secondary “razor vortex” when the shearing between the fuel jet and the coflow switches direction.